/**
 * @Author: Lenovo
 * @Date: 2024/7/14 22:31
 * @description:
 */
public class MyLinkedList {
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode last;
    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if (head == null && last == null){
            head = last = node;
        }else{
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if (head == null && last == null){
            head = last = node;
        }else{
            last.next = node;
            node.prev = last;
            last = node;
        }
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){

        int len = size();
        if (index < 0 || index > len){
            System.out.println("index位置不合法");
            return;
        }
        if (index == 0){
            addFirst(data);
        }
        if (index == len) {
            addLast(data);
        }
        ListNode node = new ListNode(data);
        ListNode cur = head;
        while (index != 0){
            cur = cur.next;
            index--;
        }
        node.next = cur;
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while (cur != null) {
            if (cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                //开始删除
                if (cur == head){
                    head = head.next;
                    if (head != null){
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next == null){
                        last = last.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                    return;
                }
            }
            cur = cur.next;
        }
    }

    public void remove1(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                break;
            }
            cur = cur.next;
        }
        if (cur == head){
            head = head.next;
            head.prev = null;
            return;
        }
        if (cur == last){
            last = last.prev;
            last.next = null;
            return;
        }
        cur.prev.next = cur.next;
        cur.next.prev = cur.prev;
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                //开始删除
                if (cur == head){
                    head = head.next;
                    if (head != null){
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next == null){
                        last = last.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                }
            }
            cur = cur.next;
        }
    }
    //得到单链表的长度
    public int size(){
        ListNode cur = head;
        int size = 0;
        while (cur != null) {
            size++;
            cur = cur.next;
        }
        return size;
    }
    public void display(){
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }
    public void clear(){
        ListNode cur = head;
        while(cur != null){
            ListNode curN = cur.next;
            cur.next = null;
            cur.prev = null;
            cur = curN;
        }
        head = last = null;
    }
}